This invention relates to a composition suitable for forming concrete having a high damping capacity, to the concrete products produced therefrom, and to a process for forming concrete.
Prior to the present invention, a wide variety of cement based compositions containing particles formed from natural and synthetic polymer compositions have been prepared. Such polymer compositions were added in the hope of improving the mechanical characteristics of the concrete, especially loading and damping characteristics. Unfortunately, these compositions have been less than successful because the polymer particles seriously reduced the strength of the concrete composition. Furthermore, such polymers often failed to be distributed homogeneously and as a result, the cured concrete had weak spots where the polymer particles were present in high concentration. Also, the polymer particles tended to work themselves out of the concrete as it was subjected to stress over an extended period, thus further weakening the concrete.
Currently, standard concrete compositions have a water/cement weight ratio of about 0.45 to 0.50. This ratio optimizes the workability of the composition so that homogeneous mixtures can be obtained. Increased amounts of water further improve workability, but the structural strength of the resulting hardened concrete is correspondingly reduced.